When to go to Strasbourg
Strasbourg is a charming city year-round, with lots of things to do in both summer and winter. However, most visitors arrive between May and September when the weather is the most reliable. And of course, the season that brings the city most afflux in visitors is summer. Things are busier in high season, but despite the crowds, summer in Strasbourg is lovely because much of everything moves outdoors. If you prefer to avoid crowds, though, the best choice would be October.
Strasbourg has a semi-continental rather humid climate, with warm, sunny summers and chilly winters. Thus the coldest months are January and December, whereas the warmest months are July and August, when average temperatures score around 22ºC. Generally, though, despite unpredictable rain and thunderstorms, in usual year conditions the city is welcoming.
You can also enjoy strolls on the old streets and take a peek at the houses and civilization signs both in spring and autumn when the evenings are mild and the mornings still shinny, which might easily pass as the best weather around. This is also when most of the street events actually occur in Strasbourg.